2. Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Autotrophs
Autotrophs are organisms that obtain energy by making their own food. (sugar-glucose)

3. What do we call the energy sources (molecules) that are used for biological chemical reactions?
ATP and NADPH

4. ATP ATP and NADPH are both biological energy storage molecules
ATP: adenosine triphosphate
ATP is the most important provider of chemical energy

5. ATP Structure

6. ATP

7. ATP: The Unit of Cellular Energy
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
ATP releases energy when the bond between phosphate groups is broken

8. Forms adenosine diphosphate (ADP) and a free phosphate group.

10. Think of ATP as a fully charged battery
ADP (adenosine diphosphate) as a half charged battery
AMP (adenosine monophosphate) as an empty battery
Which provides the most energy?

11. How is ATP made?

12. ATP is formed during photosynthesis

13. Photosynthesis: the process by which green plants use the light energy to produce carbohydrates
6CO2 + 6H2O → C6H12O O2
carbon dioxide + water (light) glucose + oxygen

14. In other words, light energy is converted into chemical energy!

15. Photosynthesis occurs in two phases.
Chapter 8
Cellular Energy
8.2 Photosynthesis
Photosynthesis occurs in two phases.
Light-dependent reactions
Light-independent reactions (Calvin Cycle)

16. Light Dependent Reaction
Energy from the sun is absorbed by the chloroplasts found mainly in green leaves
The light energy is used to produce two energy-storing molecules ATP and NADPH

17. Leaf Cells with Chloroplasts

19. The light dependent reaction occurs in the thylakoids where the chlorophyll (green pigment) is located
A stack of thylakoids is called a granum
Stroma: Fluid-filled area outside of the thylakoid

20. Draw the Following:

21. The O2 is released as waste
Light energizes the electrons found in the chlorophyll molecules
The light energy also causes a water molecule to split into 2 hydrogen and one oxygen
The O2 is released as waste

22. Through a series of events, the excited electrons are transported to an electron carrier called NADP+
The electrons bond to the NADP+ and form the chemical energy-storage molecule NADPH

23. The H+ (hydrogen ions) stay in the thylakoid and accumulate until they move out of the thylakoid space through ion channels called ATP synthases
As H+ moves through ATP synthase, ATP is formed in the stroma from ADP

24. ATP Synthase
Thylakoid
Stroma

25. ATP and NADPH are not stable enough to store energy for long periods of time
Instead, it is stored as glucose in the plant
This occurs during the second phase of photosynthesis called the Calvin Cycle or the Light Independent Reaction

27. Light Independent Reaction (Calvin Cycle)
Light Independent Reaction: uses energy stored in ATP and NADPH to make glucose
Occurs in the stroma during light or dark

29. Light Independent Reaction
Hydrogen and energy from the light reaction combine with CO2 from the atmosphere to form glucose
Glucose can store energy for long periods of time
6CO2 + 6H2O → C6H12O O2